Fermion: DS3231 Precise RTC (Breakout)

The Fermion DS3231 Precise RTC Breakout is an ultra-accurate real-time clock module designed for microcontrollers and embedded projects requiring dependable timekeeping. Featuring an integrated temperature-compensated crystal resonator and backup battery support, it is ideal for students, makers, and educators building data loggers, automated timers, and IoT systems.

High-accuracy temperature compensation

The onboard DS3231 integrates a crystal resonator and temperature compensator to minimise drift across fluctuating ambient conditions. It maintains a timing precision of plus or minus 3.5ppm, or approximately 0.3024 seconds per day, across operating temperatures from -40°C to +85°C.

Full calendar and dual alarms

The module tracks seconds, minutes, hours, day of the week, date, month, and year from 1970 to 2100 with automatic month-end and leap-year corrections. It provides 12-hour or 24-hour time formats, two programmable time-of-day alarms, and a configurable square-wave output.

Battery backup and low power draw

An onboard battery holder accommodates a CR1220 coin cell, allowing the RTC to maintain timekeeping seamlessly when main power is disconnected. Operating at an ultra-low timing current of 840nA, the module preserves battery life during extended offline periods.

Standard I2C microcontroller wiring

The board operates over a 3.3V to 5.5V supply voltage and communicates via standard I2C at address 0x68. An RST pin is also broken out to allow external push-button resets for your host microcontroller.

Compact breakout board overview

Measuring only 22.5 by 21mm, the compact footprint fits easily into tight project enclosures and prototyping boards. Each unit ships with a 2.54mm 7-pin single-row male header for quick breadboard assembly.

Crystal-based precision design

Equipped with an integrated crystal oscillator, this breakout balances low timing current with high clock accuracy for battery-conscious embedded systems.

Downloads & documentation

• Product wiki (DFRobot)